The Colorful Smell of Richard Dawkins

How do we know that your ‘red' looks the same as my ‘red'? For all we know, your ‘red' looks like my ‘blue'. In fact, for all we know your ‘red' looks nothing like any of my colors at all! If colors are just internal labels, then as long as everything gets labeled, why should your brain and my brain use the same labels?

Richard Dawkins recently wrote a nice little piece on color, and along the way he asked these questions.

He also noted that not only can color labels differ in your and my brain, but perhaps the same color labels could be used in non-visual modalities of other animals. Bats, he notes, use audition for their spatial sense, and perhaps furry moths are heard as red, and leathery locusts as blue. Similarly, rhinoceroses may use olfaction for their spatial sense, and could perceive water as orange and rival male markings as gray.

However, I would suggest that most discussions of rearrangements of color qualia severely underestimate how much structure comes along with our color perceptions. Once one more fully appreciates the degree to which color qualia are linked to one another and to non-color qualia, it becomes much less plausible to single color qualia out as especially permutable.

Few of us, for example, would find it plausible to imagine that others might perceive music differently, e.g,. with pitch and loudness swapped, so that melody to them sounds like loudness modulations to me, and vice versa. Few of us would find it plausible to imagine that some other brain might perceive ‘up' (in one's visual field) and ‘down' as reversed. And it is not quite so compelling to imagine that one might perceive the depth of something as the timbre of an instrument, and vice versa. And so on.

Unlike color qualia, most alternative possible qualia rearrangements do not seem plausible. Why is that? Why is color the butt of nearly all the "inverted-spectra" arguments?

The difference is that these other qualia seem to be more than just mere labels that can be permuted willy nilly. Instead, these other qualia are deeply interconnected with hosts of other aspects of our perceptions. They are part of a complex structured network of qualia, and permuting just one small part of the network destroys the original shape and structure of the network - and when the network's shape and structure is radically changed, the original meanings of the perceptions (and the qualia) within it are obliterated.

The reason other qualia seem to be more than mere labels is that most of them have clear meanings and functions. We know what they're for, and how they plug in to the rest of our network of qualia. For color, on the other hand, we have historically been largely blind to what colors are for, and how they functionally integrate with the rest of our perception. In the absence of knowing how to plug colors in to the rest of our qualia, they do seem much more rearrangeable.

But we're beginning to know more about what colors are for, and as we learn more, color qualia are becoming more and more like other qualia in their non-permutability. Let's see why.

First, even before describing some of the new insights on color vision, I note that most conversations about color qualia don't seem to account for what has long been known about colors. Colors are not a set of distinct crayons with no connections to one another. Instead, colors are part of a three dimensional space of colors, a space having certain well-known features. The space is spanned by a red-green axis, a yellow-blue axis, and a black-white axis. These three axes have opponent colors at opposite ends, and these extreme ends of the axes are pure or primary (i.e., not being built via a combination of other colors). All the colors we know of are a perceptual combination of these three axes. For example, burnt orange is built from roughly equal parts yellow and red, and is on the darker side of the black-white dimension.

To perceive colors like I do requires, at a minimum, having the same color space as I do. To perceive ‘red' without having (its opposite) ‘green' also as part of one's color space is impossible, just as perceiving ‘light' would be impossible without also having ‘dark'. And to perceive orange without having both red-green and yellow-blue axes is impossible, because orange is a perceptual mix of red and yellow.

And that's just the bare beginnings of the structure of colors. Colors are not only intricately connected to one another in a space, but are linked to many other aspects of our mental life, including other sensory modalities (e.g., a "red sounding trumpet") and emotions.

In fact, in my research I have provided evidence that our primate variety color vision evolved for seeing the color changes occurring on our faces and other naked spots. Our primate color vision is peculiar in its cone sensitivities (with the M and L cones having sensitivities that are uncomfortably close), but these peculiar cone sensitivities are just right for sensing the peculiar spectral modulations hemoglobin in the skin undergoes as the blood varies in oxygenation. Also, the naked-faced and naked-rumped primates are the ones with color vision; those primates without color vision have your typical mammalian furry face.

In essence, I have argued elsewhere that our color-vision eyes are oximeters like those found in hospital rooms, giving us the power to read off the emotions, moods and health of those around us.

On this new view of the origins of color vision, color is far from an arbitrary permutable labeling system. Our three-dimensional color space is steeped with links to emotions, moods, and physiological states, as well as potentially to behaviors. For example, purple regions within color space are not merely a perceptual mix of blue and red, but are also steeped in physiological, emotional and behavioral implications - in this case perhaps of a livid male ready to punch you.

Furthermore, these associations are not arbitrary or learned. Rather, these links from color to our broader mental life are part of the very meanings of color - they are what color vision evolved for.

The entirety of these links is, I submit, what determines the qualitative feel of the colors we see. If you and I largely share the same "perceptual network," then we'll have the same qualia. And if some other animal perceives some three-dimensional color space that differs radically in how it links to the other aspects of its mental life, then it won't be like our color space. ...its perceptions will be an orange of a different color.

What do you mean by "the qualitative feel of the colors we see" Mark? I assumed that to see color is also feeling it (sensed), given that the particular sensitivity of the eye is being stimulated by a particular light-speed that makes a particular color. When you use "qualitative" does this mean a measure of, say, the color red when compared with blue, therefore, adding an emotion to the observed and particular vibratory frequency that red is?

By the "qualitative feel of red", say, one refers "what its like to experience red". When we see red, versus blue, and versus completely different modalities of perception, we experience it in a certain way. The question people like to ask is whether your experience of redness is that of mine -- are our "qualitative feels" the same?

Ah, so it is our (each experiencer) difference emotionally? Each of our emotional attachment or non-attachment (or degrees thereof) to a color? To express this "qualitativeness" to another experiencer wouldn't one then need to use further allegory or poetic licence in order to "get across" this feeling? (I say "further" because even the noise "red" is allegorical of some vibration phenomena that falls under the "allegorical" label called "color").
Wouldn't it be more informative, for positive developement toward intimate human relations (being a psychology site), to consider the vibration phenomena we call "emotion" and, therefore, "cut to the chase" considering that color is on a more gross or superficial plane of experience than emotion (which you seem to be "getting at", anyway, with this "qualitative" thing)?

No, I didn't mean to suggest it is just emotional. That's part of it, yes, and that's what I'm emphasizing in the piece. But the "qualitative feel" refers to the entirety of "what it's like" to experience redness. That includes that look of red, however one might want to phenomenologically characterize it. My point is that its entire "look" is due to how it sits within the entire perceptual network, including links to emotions, behaviors, and so on.

And I'd argue that, despite first appearances, color is not quite as superficial as we usually think. It's not just a label for the spectral reflectance of a surface in the world, but a much much richer kind of perception. ...about moods, emotions, behaviors...

Well you mentioned "3" things,"..about moods, emotions, behaviors" but, really, they are one. Mood IS emotion and behaviour IS how we relate on an emotional level. I would further contend that ALL things are emotional, including all the colors of the rainbow. All colors merely reflect is the "mood" of human experience. Therefore, ALL human experience is (merely) a reflection of Reality. Just as an emotional feeling is a reflection of Feeling in it's entirety (feeling of "one with everything"). An emotion is a limitation on Feeling. Just as an "individual" color is a limitation on the Full spectrum of Light.

I'm disappointed that your article didn't explore the objectivity/subjectivity of smell. I think smell is more objective than most people realize, except that we're not taught a good labling system as children so don't know how to talk about smell.

The problem for a scientist about olfaction is not that it is different than the other senses in regards to objectivity. The problem is simply that it is really really complicated! Vision, for example, can be understood as a visual field view of a 3D world, with distances perceived, and colors (themselves falling into a simple-ish three-dimensional color space), and so on. Complicated, but doable. But smell...there's potentially a thousand dimensions that our noses can smell, and there's no obvious way to even begin thinking about how to understand it. Olfaction, I am not worthy.

Noun: "I smell smoke" (to perceive the odor or scent of through the nose by means of the olfactory nerves) Noun: "The smell of cut grass filled the air" (the quality of a thing that is or may be smelled)

"So there's actually a bridge of neural tissues in these twins, which makes them quite unique." [...] "They share a lot of things normal conjoined twins don't," she said. "They have special abilities to see each other, see what each other's seeing through each other's eyes." http://abcnews.go.com/widgets/mediaViewer/image?id=10893750

Hi. Color blindness is (almost always, and almost always just men) is when one has only two cones, more akin to what your typical mammal possesses. One has black-and-white, and yellow-and-blue dimensions. What one misses is the red-green dimension. And without the cone they "should" have, they mostly lose their ability to sense oxygenation modulations in the skin/blood. There's a long history of color blind doctors noting how handicapped they are at sensing the states of their patients, for example. What I'd *like* to look for is evidence that color blind people (again, mainly males) have a lower ability to sense emotions in others. No data on that yet.

Great article, Mark. One question: What do you make of synesthesia? Apparently (according to Wikipedia) it's common for synesthetes to identify "A" as with "red." Is there something about the universal perception of red that identifies with a (probably much less universal) perception of "A"?

I don't know about the "A"-red case, but there's lots of grist to begin looking for such connections, and cross-modal ones as well. That is, on one way of viewing synesthesia, one says, "Gosh, these perceptual labels in one modality get linked for no reason whatsoever onto those perceptual labels in that other modality." But, instead, my bet is that the links come in regular patterns, due to the fact that they share similar fundamental meanings. Red, for example, can often indicate anger, and angry faces come with universal facial expressions, including an increase in the angularity of the expression (especially in the brows). One might expect that geometrical shapes found on angry faces will more commonly associate with the color of an angry face (namely, red). I talk a lot about cross-modal associations with audition in the upcoming book on music and speech, due out next year, btw.

Oh, I should have mentioned... In light of angry eyebrows, which are roughly "V" shaped, I wondered whether there was a historical propensity for visual symbols with a "V"-like shape to be associated with warning or danger. We examined several thousand symbols, and "V" shapes were much more likely to have a meaning along those lines compared to upside-down-V shapes, and both were more likely than alternative shapes.

Thanks for a great article, Dr. Changizi. Informative, and well written.

You make some great points about the evolution of color vision and how this relates to our perceptions. However, I am still a bit skeptical of the sameness of our qualia.

Here is my understanding of what you are saying: A qualia is completely determined by the evolutionary history of its attached color, by the emotions, functions and relations it is associated with. My first question - is this a correct understanding?

My second question - why should I be convinced that these are the only factors in determining qualia? It seems like you're defining qualia as the broad "sense" (in the way Frege used sense) of a stimulus. I don't think this is the standard view of qualia (or is it?). Most views of qualia encountered assume something more mysterious, hidden in the explanatory gap between brain and mind.

Final question - Even if a qualia is in fact determined fully by all these relations described, my personal experiences with a color will then slightly alter my qualia away from yours. While we share a vast evolutionary history, my emotions, my actions relating to the color will differ. This seems as if it will produce some differences in our qualia.

I'm sorry if my understanding of your article is completely off. If its not, I think your understanding of qualia is really fascinating. Rejecting causal mysteriousness is a very powerful idea. Have you written any more on this?

Final question first... People from different cultures will still tend to have their colors in roughly similar spots within their overall network, I'd claim, and to that extent they'd be experienced similarly. But I agree that, to the extent that peoples' networks aren't identical, their qualia won't be identical.

On the second question, my main aim of the piece was not to go at the problem directly, but indirectly. Qualia-rearrangement arguments are most compelling to people when applied to color, but not to most other aspects of perception. I'm arguing that these arguments, if they are worrying at all, are worrying to all aspects of our perception, not somehow especially to color (color being just as plugged-in to the rest of our network as the other stuff). Musical pitch and loudness don't seem interchangeable for obvious reasons -- their structures and how they link to the rest of our network aren't isomorphic. And I'd suggest that colors are not invertible for similar reasons.

More generally, I'm arguing that if you and I have very different networks, then our qualia will differ.

The harder part is the other way around, namely that if you and I have very similar networks, then our qualia will be similar. That's what I'm suggesting, but ultimately to actually "prove" this (which amounts to the "hard problem") in some appropriate philosophico-mathematico-computational sense is currently beyond me! (And although I have worked in philosophy before, e.g., on the riddle of induction, I've avoided getting into consciousness, mostly for the lack of any good idea on my part.)

I understand that you've avoided getting into consciousness, but it seems to me that you have a good idea when you write: "qualia seem to be more than mere labels is that most of them have clear meanings and functions. We know what they're for, and how they plug in to the rest of our network of qualia". I believe that a solution to the hard problem of consciousness might be that the brain is a theater in which neural processes or functions become qualia when a network of meanings arises. Thus the color red, the smell of powder, the feeling of hotness, the sense of I, the sensation of pain, etc., all are conscious because they each have a function that becomes 'salient' for the organism's fate, and, as they play a part on the stage of the brain, they each convey a meaning which is a part of the narrative from which emerges a conscious experience.

Why do you think that people from different cultures have their colours in similar spots? I was wondering if people have their networks tweaked for maximum distinguishing capacity amongst their own race..

I've come across articles where they talk about how different cultures have different distinguishing capacities for different colours based on the vocabulary they have. Does an illiterate & deaf/dumb person have less richness in his visual field?

Also, I've read about how synesthesia can be induced via hypnosis. When this is done, can any grapheme be linked to any colour? Can an unused colour be accessed this way?

Why would it matter?
If the auditory stimulus generated a similar emotion to that of the visual stimulus that is "red-green", then is emotion not the important factor? There seems to be no need for the use of imagination in the way you imagine. Why should we imagine that our (shallow or superficial) experiences be the same? Is it not more to have deeper shared experiences (at that "emotional" level)?

IMO, the subjectivity of color is best solved with a hardware/sofware analogy.

If all of us have a retina, nervous system, brain, etc. that quantitatively just slightly differs from everybody else's, then the color input (and by extension the input of any physical stimuli) shall be in the same degree similar between all of us.

So my blue is yours blue too!

On the other hand, it may be argued that not everybody *perceives* consciously (i.e. by their implicit "software") "all the shades of blue" that the "hardware" is in principle able to offer.

In such context, isn't a "blue" stimuli always something more than just a color?

I think the social function of color perception comes much later than possible preliminary functions of it. Yes, we now use our color perception to discriminate all sorts of things, but in the beginning it must have served much simpler needs. Think of the environment our ancestors evolved: sky and clean water are blue, plants are green (chlorophyll), bare soil is red(I know it's brown but most dominant color component of it is red) and red also helps identifying other animals and humans(which have colors like yellow, pink, brown, orange...) and also blood and meat. We have three kinds of cone cells in our eyes each of which sensitive to just right frequencies in the spectrum for all the important things in our lives. I think this is a much better explanation for the purpose of color perception and why it cannot differ from person to person too much.

As you are no doubt aware, color is not an objective reality in the physical world. The wavelength of light does not become a color until a brain decides that it is such. In this way color is distinct from every other sense that we have because it is completely imaginary, like pain, taste, and odor. Pressure and temperature, direction of movement, and room layout are the only qualia that objectively come from the environment. Indeed, the fact that retinal photoreceptors STOP signalling upon incident photon, the huge number of intervening variables that determine color qualia and its distinct NON-linearity with photon frequency, and the similarity of retinal and all the rest with other sensory transducing molecules, the complete arbitrariness of visual stimuli without the other senses to orient, and the fact that decreased olfaction related genes combined with increased processing of vision suggest that color originated with taste or olfaction and was coopted later when visual acuity served more reliable in distinguishing individual identity than smell. Color illusions show that the same hue isn't the same from within a single person across time, much less to believe it is invariant across people, knowing colorbliness etc. In fact, one would suspect that color blind individuals could use their non-photoreceptor linked qualia for something else. Who knows, maybe they do. But clearly, the cones in the retina have become better in humans to reliably distinguish color yes, but color existed in the brain before that.